Just some notes on my findings. In regards to the Drag times for the 56 
D500-1 the published numbers for the D500 with a single carb included a 
track  record in early 56 running 15.3 at under 90 mph in California. I 
haven't got time to dig up the article now but will look it up if anyone is 
interested. Contrast this with the Ed Lyons D500-1 winning in races (with only 
MPH recorded) once at 102 in Ohio another at 106 in Sturgis Kentucky 
with the Kentucky run being nearly 20 mph faster than the single carb 
California car. Ed Lyons was interviewed by Dennis Kennedy who published the 
most comprehensive 56 D500 article to date and Ed stated he could get in the low 
14 sec range. These will be the only records available right now so take them 
for what they are worth. The big problem here is that NHRA did not allow 
multiple carbs in Stock classes in 56 and this left the D500-1 guys running 
mostly in the AATA Drag series which had formed a class called Super Stock, the 
NHRA continued this class in 57 when it merged with the AATA. On the NASCAR 
scene much to the credit of Carl Kiekhaefer the Dodge did get the D500-1 engine 
recognized as a factory assembly albeit at a very conservative 276 HP. This 
assembly included the Keikhaefer cast Aluminum intake and the super rare 4 bolt 
flange exhaust manifolds. This was significant for Dodge in that while Chrysler 
did get the large 4 bolt flange manifolds approved for optional use in 56 the 
engine did not officially appear as a 355 HP assembly in NASCAR and no 
known assemblies were sold. After March 9 th  1956 you could special order 
a 56 D500 with the NASCAR Dual Quad assembly, how many were produced is not 
known. To get this assembly buyers would have to forgo the automatic 
transmission and power steering. The dual quads can be added to an 
automatic D500 after the fact but the exhaust manifold are not compatible with 
the power steering due to clearance. The 315 D500-1 manifolds 
are by far the rarest of the 56 D500 parts as they only appeared on 
the late NASCAR assemblies and were not used on other assemblies like the truck 
and industrial engines. Tim in Golden 56 D500-1